Process of producing ferrous oxid



UNITED STATES PATENT OFFICE. ARCHIBALlD J. MAODOUGALIi, OF TORONTO, ONTARIO, CANADA, ASSIGNOB,

AND MESNE ASSIGNMENTS, OF ONE-SIXTH '10 HERBERT C. BUGNIRD, OF NEW YORK, N. Y., ONE-SIXTH TO JAMES G. ROWE AND ONE-HALF TO BAY H. BENNETT,

BOTH 0! NORTH TONAWANDA, NEW YORK.

PROCESS OF PRODUCING FERROUS OXID.

No Drawing.

To all whom it may concern.

Be it known that I, ARCHIBALD J. MAC- DoUoALn, a subject of George V, King of the United Kingdom of Great Britain and Ireland, residing at Toronto, in the Province of ()ntario and Dominion of Canada, have invented certain new and useful Improvements in Processes of Producing Ferrous Oxid; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art towhi'ch it apperta-ins to make and use thesame.

My invention relates to the manufacture of ferrous oxid by an electrolytic process.

At present it is customary to produce ferrous oxid by treating iron with sulfuric acid to obtain a sulfate of iron solution. This solution is then concentrated by evaporation and crystallized. The crystals are subsequently calcified, thus producing ferric oxid, which latter is then reduced by hydrogen to form the ferrous oxid. This well known process not only necessitates the use of sulfuric acid, an alkali and hydrogen, but it also involves five distinct operations, namely, the formation of the sulfate of iron, the evaporation of the sulfate solution, the crystallization, the calcining to produce the ferric oxid, and the reduction of the oxid to the ferrous form by the use of hydrogen; and in addition the present process of manufacture has the d: lvantage of often producinga product whlch is not entirely ferrous oxid but contains some iron. Moreover, theapparatus required in making the sulfate of iron solution and in concentrating it and effecting crystallization has to be replaced frequently because of rapid deterioration due to the action of the acid thereon; and a further disadvantage of the process at present followed is that the reduction of the ferric oxid by hydrogen requires heat, and great care must be taken with the product to prevent its oxidation in the air to the ferric state due to its pyrophoric condition. The apparatus required in the practice of my process is much cheaper, simpler and more easily maintained than that now employed in the production of ferrous oxid, the cost of making the product is less and liability of iron being produce% along with the ferrous oxid is minimlze Specification of Letters Patent.

Application filed August 21, 1920. Serial No. 405,055.

My process consists in forming ferrous oxrd from iron in an electrolytic cell in which the iron that is to enter into the ferrous o x1d constitutes the anode,.the cathode belng any conductor which is insoluble in the electrolyte, and the electrolyte being an aqueous solution of a salt. The iron of the anode 1s replenished as may be necessary from time to time as the production of the oxid proceeds; the cathode is preferably iron or may conveniently be made of carbon; and the electrolyte is preferably an aqueous solution of sodium chloridor of sodium sulfate, the former being more advantageous on account of its low cost and because its solubility does not vary greatly with heating and also because of its low reslstivlty.

When a direct current is passed through the anode, electrolyte and cathode, the salt of the aqueous solution is broken up, releaslng an acid at the anode and an alkali at the cathode. The released acid dissolves the anode into an iron salt and the alkali released at the cathode, acting on this salt, precipitates out ferrous oxid of iron from said salt. The ferrous oxid is then removed from the cell. 1

After the ferrous oxid has been removed from the cell it is freed of its moisture content. This may conveniently bedone by extracting a portion of the moisture by means of a filter press and by drying the ferrous oxid cake from the press in the presence of an inert or a reducing gas, the latter being preferable because a slight amount of an occluded reducing agent tends to prevent oxidation of the product from the ferrous to the ferric state, thus increasing the stability of the compound as placed upon the market. Excellent results are obtained in the drying operation if thetemperature of the reducing agent does not exceed 500 F.

Assuming that an aqueous solution of sodium chlorid is adopted for the electrolyte, the reactions occurring in the production of {he ferrous oxid within the cell are as folows:

(II) Fe+2C1-- Fe0l,

(III) Feel, 2NaOH- FeO 2NaCl H,o The aqueous solution of sodium chlorid is electrolyzed to sodium hydroxid, chlorin, and hydrogen. The chlorin liberated by the electrolysis combines with the iron of the anode and forms chlorid of iron which is in turn acted uponby the sodium hydroxid produced by the electrolytic action, thus producing ferrous oxid and sodium chlorid, the hydroxtyl radical bein broken up in the course 0 electrolysis. he ferrous oxid is the desired product. The sodium chlorid is again electrolyzed, the action of the aqueous salt being cyclic.

The hydrogen which bubbles up through the electrolyte agitates it so that the iron salt formed there is brought into contact with the sodium hydroxid produced at the cathode,

the result being that the reaction between the iron salt and the sodium hydroxid takes place readily and rapidly. If desired the hydrogen given off may be collected and used as a reducing gas in the drying of the ferrous oxid.

While in the example given sodium chlorid is the salt employed, it has been found that other soluble salts, particularly those of the so-called alkali metals, are applicable.

I claim 1. The process of producing ferrous oxid which consists in subjecting iron to the reaction in a cell of the products of the elecsolution of a salt in the presence of an iron anode and a cathode which is insoluble in said aqueous solution.

4. The process of producing ferrous oxid which consists in subjecting iron to the reaction in a cell of the products of the electrolysis of an aqueous solution of a salt, and subsequently drying said ferrous oxid in the presence of a reducing gal.

5. The process of producing ferrous oxid' which consists in sub ecting iron to the reaction in a cell of the products of the-electr(1)lysis of an aqueous solution of a sodium sa t.

6. The process of roducing ferrous oxid which consists in su jecting iron to the reaction in a cell of the products of the electrolysis of an aqueous solution of sodium chlorid.

7. The process of producing ferrous oxid which consists in electrolyzing an aqueous solution of a sodium salt in the presence of an iron anode and a cathode which is insoluble in said aqueous solution 8. The process of producing ferrous oxid which consists in electrolyzing an aqueous solution of sodium chlorid in the presence of an iron anode and an iron cathode.

9. The process of producing ferrous oxid which consists in subjecting iron to the reaction in a cell of the products of the electrolysis of an aqueous solution of a salt, and subsequently drying said ferrous oxid in the presence of hydrogen.

10. The process of producing ferrous oxid which consists in electrolyzing an aqueous solution of sodium chlorid in the presence of an iron anode and an iron cathode, and subsequently drying said ferrous oxid in the presence of hydrogen.

11. The process of producing ferrous oxid which consists in subjecting iron to the reaction in a cell of the products of electrolysis of an aqueous solution of a salt of an alkaline substance.

12. The process of producing ferrous oxid which consists in subjecting iron to the reaction in a cell of the products of theelectrolysis of an aqueous solution of a salt, said solution containing a salt of an inorganic acid dissolved therein.

ARCHIBALD J. MACDOUGALL. 

